This invention relates to interconnecting of wooden members, and more particularly to the interjoining of wooden timbers or boards to produce beams, columns, headers or other composite assemblies for use in the construction of buildings or the like. The invention is based on an improvement over certain of the concepts disclosed in the above-identified patents, and especially over the concepts disclosed in U.S. Pat. No. 3,090,088.
In that patent, a connector device is disclosed which generally comprises a flat metal truss plate having a plurality of openings therein, with a plurality of prongs formed at the opening edges and extending unidirectionally outwardly of one plate face. According to the description in the patent, the prongs are formed so that, upon placing the connector device across the exposed outside joint portion of abutting wood members with the prongs facing the wood, and then applying compressive forces, the prongs enter the wood and bend or flare outwardly to clinch the wood between prongs of adjacent openings. When such connector devices are mounted to the opposite faces of the exposed joint between a pair of abutting board ends, a strong structure is created.
In the construction of buildings or the like, it is often desirable to utilize a beam or column which comprises a plurality of boards which are arranged in abutting face-to-face relationship, rather than in an end-to-end relation such as is contemplated in U.S. Pat. No. 3,090,088. The resultant composite or laminated beam or column of boards serves as a substitute for an integral post made from a single piece of wood, which can be quite expensive. See, for example, U.S. Pat. No. 4,479,342. Heretofore, the composite laminated structure has often been created by nailing or bolting the boards together in facing relationship, a procedure which has not always been found to be fully adequate or permanent.
It has also been suggested to join the faces of adjacent boards, as by connector devices which utilize straight nails or triangular barbs extending outwardly from both faces of a base plate. See, for example, U.S. Pat. Nos. 797,083, 1,806,522 and 4,429,500. The known devices of these patents are subject to numerous disadvantages, such as being only temporary or requiring supplemental bolting or being basically unworkable without external supports, respectively. Their contemplated connecting constructions are not nearly as efficient as that of the aforesaid U.S. Pat. No. 3,090,088 which utilizes the one-sided clinching prong structure.
It is a task of the present invention to make it possible to construct a multi-layered or laminated wooden beam or column which utilizes the superior concepts of the U.S. Pat. No. 3,090,088 throughout. It is a further task to construct such a beam or column structure without the need for supplemental connectors such as nails, bolts, truss plates and the like. It is another task to make it possible to manufacture a multi-layered beam or column which includes at least some short, and thus inexpensive, pieces, and wherein only a portion of the member need be treated with a wood preservative. It is yet another task to modify the connector structure disclosed in U.S. Pat. No. 3,090,088 in such a manner that the previously mentioned tasks may be more easily accomplished, and wherein the composite wood structure is permanently joined synergistically and can carry a load independently of any additional support or connector device for the structure itself.
In accordance with the various aspects of the invention, the specially formed prongs of U.S. Pat. No. 3,090,088 are struck outwardly from adjacent openings in the plate in directions which are opposite from each other. Thus, each face of the base plate includes alternate openings in blank, and openings from which extend a set of prongs generally normal to the plate. The advantage of being able to clinch the wood when compressive forces are applied is thereby made available to both sides of the connector base plate so that the connector device is usable to laminate multiple layers of boards in face-to-face relationship, which was not possible or contemplated in the original structure of U.S. Pat. No. 3,090,088.
In manufacturing beams or columns using the improved connector device, and in one embodiment, at least one long jointless board is provided, with a plurality of short boards generally equaling in total length the longitudinal extent of the long board being positioned in facing relationship with the latter. The connector device of the invention is positioned between the faces of the long and short boards, with the prongs extending across the abutting joint between each pair of short boards. Compression is then applied to the assembly, which forces the oppositely extending prongs into the opposed board faces until the assembly forms a tight unitary structure with the prongs clinching the wood in the boards on both sides of the connector. The connector itself is generally buried within the composite structure and is not exposed to undesirable accidental external forces, such as being hit and weakened by a swaying metal beam or the like during construction. In the areas remote from each abutting joint, further connector devices may also be placed to stabilize the beam or column against lateral sliding or swinging of the wood members in the plane of the interface therebetween.
In another embodiment, each layer in a composite multi-layer construction comprises a plurality of short boards of different lengths, with the joints between abutting board ends being offset longitudinally from each other. The length of each layer is normally the same as the length of every other layer.
When more than two layers are included in the final assembly, a layer may include a single board, or multiple abutting boards.
In the various embodiments contemplated, no external truss plate need be used at any exposed outer joint portion disposed between abutting boards.